I already contacted the support, but since the first troubleshooting advice didn't help and I'm still waiting for an answer, I'll ask here, it might help someone someday.
ACS crashed while I was reinstalling several plugins last week, and since then I can't access it at all. Authorization seems to work, but when I launch the software, I just get Windows top bar and nothing else, collapsed box. Of course, I tried reinstalling it a few times and tried tinkering the compatibility modes, but nothing fixes the problem.
Support told me it was OpenGL issues, but that's not it, it worked perfectly fine until now, and I tested both my graphic cards (nvidia and motherboard).
It's a pity it's happening right now, because I'm considering upgrading...